The present invention relates to exercise machines, and in particular relates to an exercise machine incorporating one or more cranks and a method for use of such a machine in training selected muscle groups for athletic or therapeutic purposes.
Exercise machines are well known in which handles or pedals are used to drive cranks connected to flywheels or fans that provide resistance to rotation of the cranks. Various brakes or other mechanisms are used in other exercise machines to provide desired amounts of resistance to rotation of the cranks, varying the resistance in response to operator control, as taught by Owens U.S. Pat. No. 4,934,692, or in response to the length of time during which the exercise machine is operated, or in response to the number of rotations of the crank, as in Johannson U.S. Pat. No. 3,501,142. While such exercise machines are useful in improving the fitness of a healthy user, they are not particularly useful in providing training for rehabilitation of specific muscle groups in injured users or athletes trying to improve function of specific muscles or to improve a particular coordination pattern.
Even though every joint has two sets of muscles working about that joint (generally referred to as the agonist and the antagonist muscles; as they work in opposite directions) for most exercise machines most of the benefit has been to one set of muscles in the legs, the anti-gravity muscles (the hip and knee extensor muscles), and not to their antagonists, the other major set of leg muscles, the hip and knee flexors.
Bicycles and stationary exercise machines which utilize a pair of fixedly opposed cranks driving a flywheel require an initial effort to overcome the inertia of the flywheel or cycle and continued effort thereafter to overcome the continuing effects of friction usually provided by an adjustable brake. A pair of opposed cranks continuously connected to a flywheel, however, may result in flywheel inertia, or torque applied to one crank, being used to make up for weakness of injured muscles working on the opposite crank. As a result, muscles that need to be trained are not forced by the machine to work as much as might be desirable.
Recently there have been attempts to address this weakness of the bicycle and previously known exercise machines, and three recent patents are of note in this regard: Moser, et. al. U.S. Pat. No. 6,234,939, Day U.S. Pat. No. 5,860,329, and Taylor U.S. Pat. No. 5,496,238. The patents of Moser and Day both teach making the two pedals of the bicycle or exercise machine independent from each other to force the use of and thus provide for training of the hip and knee flexor muscles in the pedaling motion, although these two inventors went about this in different ways.
Moser's device, although claiming to be useful for bicycles, gives a description of only a stationary exercise device and achieves its end through dual right and left drive mechanisms. While it would be possible to put such a system on a bicycle it would require substantial modification of a typical bicycle.
Day's solution, while claiming to be useful for an exercise machine, gives a description only of a mechanism to attach to a standard bicycle to make the cranks independent, and it achieves its end by using independent cranks to move a single drive mechanism. Moser's device does describe allowing the user to choose different resistances for the right and left legs on a stationary exercise machine although he does not describe how one would do so on a bicycle. Neither Day nor Moser, et. al. provides significant resistance when pedaling backwards.
The device disclosed by Taylor is specifically intended to train the hip and knee flexor muscles in an independent pedaling apparatus that specifically adds resistance on the “up stroke” of the pedaling motion, but that deliberately provides less resistance on the “down stroke,” just the opposite of most cycle type exercise machines.
Some exercise machines are intended to simulate the exercise requirements of an actual bicycle ride, as by increasing braking against crank rotation to simulate climbing a hill, and decreasing braking in order to simulate descending a hill. Such previously available stationary exercise machines, however, fail to realistically simulate many of the variable requirements for effort experienced while actually riding a bicycle, such as needing to overcome the mass inertia of the rider when accelerating or decelerating and the tendency of the bicycle to accelerate when going downhill, even when not pedaling, and improvements are desired.
While some variable resistances are present in currently available exercise machines, many do not simulate the inertia of the bike/rider system which would require the user to put in enough excess energy in order to accelerate. Such system inertia would require approximately 30 seconds for a rider to accelerate to top speed, as in real world riding, compared to the 3-5 seconds it takes on currently available exercise machines where this inertia is ignored or attempted to be simulated with a large flywheel.
Another simulation defect of current machines is the inability to simulate the speeding up that occurs when coasting down hill without attempting to accelerate.
It is therefore desired to provide an exercise machine in which resistance to cranking can be varied for the purpose of training specific muscle groups, and methods for use of such a machine to train selected muscle groups and to simulate more realistically the experience of riding an actual bicycle over varying terrain.